The Ordnance BL 12lber 7 cwt marked a return to the breech loaded Field Gun used by the British Army. The Ordnance BL 12lber was used by both the Royal Field Artillery and Royal Horse Artillery, although its size and weight caused issues with its deployment.
The Ordnance BL 12lber was designed with a breech loading system, a feature that had not been seen on any cannon in the British Army since the Armstrong Breech Loading 12 pounder 8 cwt. The Ordnance BL 12lber would benefit from a simpler Breech Loading system than the older Armstrong system.
However the Ordnance BL 12lber suffered from the design of its carriage, which was overly complicated and caused issues with the deployment of the Ordnance BL 12lber when the Royal Horse Artillery were equipped with it. The carriage and Ordnance BL 12lber together were heavier than older cannon, meaning that the Royal Horse Artillery would travel slower, and therefore would be less effective.
The Ordnance BL 12lber would eventually benefit from the introduction of cordite in shells, meaning that more powerful, larger caliber Field Guns would come into the fore. The Ordnance BL 12lber would be modified to accept the larger 14lb shell, becoming the Ordnance BL 15lber.
The Ordnance BL 12lber was named for its ability to fire a 12lb shell. This shell was unique to the Ordnance BL 12lber, in actuallity weighing in at 12.5lb. The Ordnance BL 12lber would also fire a shrapnel shell of the same weight.
The Ordnance BL 12lber was an important step in the development of the Field Artillery, ending the use of muzzle loading cannon in the British Army. Despite its immediate use by the Royal Field Artillery and the Royal Horse Artillery, the Ordnance BL 12lber was not in use for a particularly long time, its complicated carriage design and weight causing issues in transportation, requiring 6 horses in 3 pairs to tow.